The list goes to only 48 because two states – Nebraska and Utah – did not have data available.

The study also looked at standards for eighth-grade reading proficiency. South Carolina, Missouri, Minnesota, and Vermont are in the top five, as they were for fourth grade. But Massachusetts, which was No. 1 in the list above, dropped to No. 10 for eighth grade. And Florida moved up to the fifth spot.

Only one state from the fourth-grade bottom – Tennessee – repeats in the lowest rankings for eighth grade. The other states bringing up the rear for eighth grade are Georgia, North Carolina, Texas, and West Virginia.

As for eighth-grade math, the highest-ranking states are the ones that were tops for fourthgrade math – except Vermont and New Hampshire come out of the list and Hawaii, Minnesota, and Maine go in.

The state at the bottom of the eighth-grade-math list is Tennessee (once again). Georgia, Oklahoma, Illinois, and Connecticut round out this group.

Using a national scale, the report determined that what states consider proficient varies by as many as 78 points.

“It’s a very big puzzle to me, how there can be such a difference,” said John Easton, director of the Institute of Education Sciences at the U.S. Education Department, according to the Associated Press.

One thing to keep in mind is that these rankings deal with state standards – not with the actual performance of students. It’s conceivable that a state has low standards, yet students there do very well. The reverse – weak performance in a high-standards state – is possible, too.